Neutron-absorbing materials

Abstract

A boron-containing polyethylene having an average molecular mass of at least 2.5x106 g/mol as a neutron-absorbing material.

I claim: 
     
       1. A neutron-absorbing material consisting of polyethylene having boron and/or a boron compound embedded therein, said polyethylene having an average molecular mass, measured by viscosimetry, of at least 2.5×10 6  g/mol. 
     
     
       2. The material of claim 1 wherein said polyethylene is predominantly linear. 
     
     
       3. The material of claim 1 wherein said molecular mass is 2.5×10 6  to 8.0×10 6  g/mol. 
     
     
       4. The material of claim 1 wherein said molecular mass is 3×10 6  to 6×10 6  g/mol. 
     
     
       5. The material of claim 1 wherein there is a boron compound present selected from the group consisting of H 3  BO 3  and B 4  C. 
     
     
       6. The material of claim 5 wherein said compound is B 4  C. 
     
     
       7. The material of claim 6 wherein said B 4  C has a particle size of 10 to 200 μm. 
     
     
       8. The material of claim 7 wherein said particle size is 20 to 80 μm. 
     
     
       9. The material of claim 6 wherein said B 4  C is present in a concentration of 5 to 50% by weight, based on said material. 
     
     
       10. The material of claim 9 wherein said concentration is 10 to 40%. 
     
     
       11. The material of claim 9 wherein said concentration is 20 to 30%. 
     
     
       12. The material of claim 1 wherein at least one stabilizer against heat, light, and/or oxidation is present. 
     
     
       13. The material of claim 4 wherein said polyethylene is linear, said compound is B 4  C having a particle size of 20 to 80 μm, and is present in a concentration of 20 to 30% by weight based on said material, and a stabilzer against heat, light, and/or oxidation is present in a stabilizer amount of 0.1 to 0.2% by weight based on said material. 
     
     
       14. The material of claim 13 wherein said stabilizer is selected from the group consisting of 4,4'-thiobis-(3-methyl-6-t-butyl-1-phenol), dilauryl thiodipropionate, distearyl thiodipropionate, tetrakis[methylene-(3,5-di-t-butyl-4-hydroxy-hydro-cinnamato)]-methane, n-octadecyl-β-(4'-hydroxy-3,5'-di-t-butylphenyl)-propionate, and glycol bis-[3,3-bis-(hydroxy-3'-t-butylphenyl)-butanoate. 
     
     
       15. The material of claim 1 wherein impurities in said polyethylene do not exceed a content of 200 ppm by weight based on said polyethylene. 
     
     
       16. The material of claim 15 wherein said content does not exceed 150 ppm. 
     
     
       17. A process for the production of the material of claim 1 comprising mixing said polyethylene and said boron and/or boron compound to form a mixture, sintering said mixture, and cooling said mixture. 
     
     
       18. The process of claim 17 wherein said sintering is at a sintering temperature of 180° to 250° C. 
     
     
       19. The process of claim 18 wherein said sintering temperature is 200° to 230° C. 
     
     
       20. The process of claim 17 wherein said sintering is at a sintering pressure of 5 to 10 MPa. 
     
     
       21. The process of claim 20 wherein said sintering pressure is 8 to 10 MPa. 
     
     
       22. The process of claim 17 wherein said cooling is at a cooling pressure of 3 to 5 MPa. 
     
     
       23. The process of claim 22 wherein said cooling pressure is 4 to 5 MPa. 
     
     
       24. The method of claim 19 wherein said sintering is at a sintering pressure of 8 to 10 MPa, said cooling is at a pressure of 4 to 5 MPa.